1. Field of the Invention
The present invention relates to an output device, a control method for the output device, and to a data storage medium for recording a computer-executable program implementing the steps of the control method. More particularly, the present invention relates to technology for quickly and easily changing the operating parameter settings of an output device.
2. Description of the Related Art
Printers, displays, and other output devices output by printing or presenting on a display monitor text and images contained in control commands and data input to the output device from a host device. The host device (referred to as simply host below) specifies values or settings of operating parameters such as the language code (JIS, ASCII, Unicode, or others), font, character and image size, and line spacing, and the output device then outputs the text and images based on the specified parameter values.
The output device typically stores these various parameter values as an operating environment in a predetermined area of RAM (Random Access Memory), and retrieves required parameter values from the RAM when the text or image data is processed for output. When output device power is turned on or the output device is reset, the operating parameters are set to default values by an initialization program. For the host device to set any particular parameter to a desired value, it must send a parameter setting command to the output device.
This means that if a default value of the output device differs from a value preferred by the host, the host must send the parameter setting command to the output device every time output device power is turned on or the output device is reset.
Some application programs (referred to as simply applications below) that run on the host also issue, during the application startup process, an initialization command that restores these operating parameters to the default values, and then after the application is running send another command to set the output device to a certain operating environment, that is, set the parameters to the values required by the application. This is because by restoring the operating parameters temporarily to their default values, the application only needs to send commands to change those of the parameters whose value should be different from the respective default value, and can thereby reduce, even if just slightly, the amount of data to be transmitted. Even with this method, however, the host needs to send a large amount of data to the output device to change the output device settings.
We should also note that Japanese Unexamined Patent Application Publication (kokai) 8-69362 teaches an output device that saves, as part of the shutdown process performed when power is turned off, the operating environment settings stored in RAM to an external nonvolatile memory. When the power is turned on, the output device checks whether the external nonvolatile memory is present and, if so, whether operating environment settings are stored in the nonvolatile memory. If such settings are stored and a restoration command is received from the host, the output device copies these saved settings from the nonvolatile memory back to the RAM.
Many applications for point of sale (POS) systems, in particular, send an initialization command to the output device at each transaction (for example, printing one receipt) in order to ensure reliable output; the operating parameters must therefore be reset to the desired values at each transaction. A problem arises in the context, when the communications rate between the host and output device is slow, a situation that is quite common. Because a large amount of data must be sent from the host to change a particular operating parameter to a desired value, a relatively long period of time is required to set the output device to the desired operating environment. It is therefore particularly desirable to have an output device that can easily set the operating parameters at high speed.
Furthermore, a single output device is often shared by plural applications. It is therefore also desirable to have an output device that can be quickly set to the operating parameters of a particular application.